Re: [PATCH v9 00/16] Add support for Clang LTO

From: Kees Cook <keescook@chromium.org>
To: Steven Rostedt <rostedt@goodmis.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	Will Deacon <will@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
	clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org,
	linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	kernel-hardening@lists.openwall.com,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v9 00/16] Add support for Clang LTO
Date: Fri,  8 Jan 2021 16:27:13 -0800	[thread overview]
Message-ID: <161015202326.2511797.6087273163265436487.b4-ty@chromium.org> (raw)
In-Reply-To: <20201211184633.3213045-1-samitolvanen@google.com>

On Fri, 11 Dec 2020 10:46:17 -0800, Sami Tolvanen wrote:
> This patch series adds support for building the kernel with Clang's
> Link Time Optimization (LTO). In addition to performance, the primary
> motivation for LTO is to allow Clang's Control-Flow Integrity (CFI)
> to be used in the kernel. Google has shipped millions of Pixel
> devices running three major kernel versions with LTO+CFI since 2018.
> 
> Most of the patches are build system changes for handling LLVM
> bitcode, which Clang produces with LTO instead of ELF object files,
> postponing ELF processing until a later stage, and ensuring initcall
> ordering.
> 
> [...]

Applied to kspp/lto/v5.11-rc2, thanks!

I'll let 0-day grind on this over the weekend and toss it in -next on
Monday if there aren't any objections.

[01/16] tracing: move function tracer options to Kconfig
        https://git.kernel.org/kees/c/3b15cdc15956
[02/16] kbuild: add support for Clang LTO
        https://git.kernel.org/kees/c/833174494976
[03/16] kbuild: lto: fix module versioning
        https://git.kernel.org/kees/c/6eb20c5338a0
[04/16] kbuild: lto: limit inlining
        https://git.kernel.org/kees/c/f6db4eff0691
[05/16] kbuild: lto: merge module sections
        https://git.kernel.org/kees/c/d03e46783689
[06/16] kbuild: lto: add a default list of used symbols
        https://git.kernel.org/kees/c/81bfbc27b122
[07/16] init: lto: ensure initcall ordering
        https://git.kernel.org/kees/c/7918ea64195d
[08/16] init: lto: fix PREL32 relocations
        https://git.kernel.org/kees/c/a51d9615ffb5
[09/16] PCI: Fix PREL32 relocations for LTO
        https://git.kernel.org/kees/c/dc83615370e7
[10/16] modpost: lto: strip .lto from module names
        https://git.kernel.org/kees/c/5c0312ef3ca0
[11/16] scripts/mod: disable LTO for empty.c
        https://git.kernel.org/kees/c/3d05432db312
[12/16] efi/libstub: disable LTO
        https://git.kernel.org/kees/c/b12eba00cb87
[13/16] drivers/misc/lkdtm: disable LTO for rodata.o
        https://git.kernel.org/kees/c/ed02e86f1752
[14/16] arm64: vdso: disable LTO
        https://git.kernel.org/kees/c/d73692f0f527
[15/16] arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS
        https://git.kernel.org/kees/c/09b812ac146f
[16/16] arm64: allow LTO to be selected
        https://git.kernel.org/kees/c/1354b8946c46

-- 
Kees Cook